Moderate the first posts of a new member
 

1) Can I set up moderation for new users only? I'd like to moderate the first messages for new members. They should not be informed in advance, most spammers would be caught on first posting while for legitimate users, moderation could lifted after a post or two.

My site and many others are quite speciallized so it would probably be quite clear after one or a few postings if the member is legitimate.

Is there such a function / mod available?

2) Another option would be to have a sentence on the signup form about why they want to join and on sentence about who they are. That would also stop many spammers / bots from signing up or at least make them easy to spot. I tried it on a forum based on my own code and it worked well.

You can modify the Registered Users group so that (new) users always have their posts moderated.

Then set up a new group (e.g., Verified Users) with the exact same permissions as the RU group, except that members of the new group do NOT have their posts moderated.

Finally, set up a promotion task (ACP->Usergroups->Promotions) so that, upon so many posts being made by the user, s/he would be promoted to the new group.

His/her posts would then be unmoderated.

Thanks for the tip!

I will do that, but without the automated promotion task, as spammers tend to mass post.